Technical Field
The instant disclosure relates to temperature control, in particular to a temperature control system and method with improved electrical power management.
Related Art
In the field of thermal management of a liquid or gas flow, temperature control via a heating device has been around for a long time. The power requirement is variable, depending on the amount of flow, desired temperature range, and the temperature change rate. Heating elements are normally resistance based, typically using tungsten wire to provide the resistance element. The liquid or gas typically flows past the heating wire, and energy is then transferred to the medium, by passing current through the wire, thus causing it to heat up. Many commercial appliances of heaters require direct current (DC) power. Hence, normally an alternating current (AC) to DC converter is used to distribute the input voltage to the point of load (POL).
The heating wire has a non-constant resistance characteristic: typically the resistance increases with temperature. The non-constant resistance characteristic makes precise temperature control difficult, since the typical way of controlling this type of heater is to turn the heater on or off, using a fixed voltage, AC or DC, thus controlling the duty cycle of the current. This type of temperature control causes undesired fluctuations in temperature and electrical noise in the system. In addition, the power factor of the supplied power is also fluctuated. These fluctuations are sometimes referred to as flicker noise, and there are limits to how much flicker noise is allowed, depending on which international standard the system has to operate within. Different locations also have varying power available, and fluctuations caused by other equipment attached to the same power can also cause fluctuations in temperature of the liquid or gas.